Two hundred ninety-four chromosomal regions contain “consecutive” recessive disease genes. A homozygous or hemizygous deletion containing two or more recessive disease genes not interrupted by a dominant or rec/dom disease gene could lead to a complex recessive phenotype (i.e., a recessive contiguous gene syndrome); heterozygous deletion of the same region may render an individual a carrier for two or more recessive conditions. Such “consecutive” recessive disease genes are indicated by the purple bars above each chromosome, which span from the start of the first recessive disease gene in the series to the end of the last one. Selected chromosomal bands are numbered for locational reference.
